I just tried coping & pasting code from How to draw Venn diagrams (especially: complements) in LaTeX
and I get errors ... I suppose I need to install/configure Lyx to use PGF/Tikz?

I just tried coping & pasting code from How to draw Venn diagrams (especially: complements) in LaTeX
and I get errors ... I suppose I need to install/configure Lyx to use PGF/Tikz?

You need to add \usepackage{pgfplots} to your preamble. In LyX, you can edit the preamble under Document | Settings | LaTeX Preamble.
\usepackage{tikz}to your preamble (I think you can do this by selectingLaTeX preamblefrom theLayoutmenu). – Jake Aug 28 '11 at 12:42\usepackage{tikz}underDocument > Settings > LaTeX preambleI still got the same error. – Jiew Meng Aug 28 '11 at 13:46\usepackage{pgfplots}too – Jiew Meng Aug 28 '11 at 13:49